Tricarbonyl rhenium(i) tetrazolato and N-heterocyclic carbene complexes: versatile visible-light-mediated photoredox catalysts

Abstract

This study demonstrates that structurally-diverse, photoactive rhenium(i) tricarbonyl complexes can mediate representative atom-transfer radical addition, hydrodehalogenation, and α-amino C–H functionalisation reactions.

Recent progress on NHC-stabilized early transition metal (group 3–7) complexes: Synthesis and applications

“…184,185 The molecular diversity of this family has been developed by varying the substituents and the nature of NHC ring: some recent examples are displayed in Figure 16 (complexes 173-175). 186,187,188,189,190 Overall, ligand structure/ photophysical properties correlations could be established thus allowing a fine-tuning of these properties. In 2020, Mauro and collaborators described a novel class of tricarbonyl Re(I) complexes bearing a pyridyl pyrido-annelated NHC as a chromophoric ligand, such as 174, which displayed a stable and long-lived, ligand-centered, red phosphorescence.…”

N‐Heterocyclic and Mesoionic Carbenes of Manganese and Rhenium in Catalysis

“…[51,52] Up to date, only one publication on photoredox catalysis with Re-NHC complexes can be found in the literature. [53] In 2019, Bissember, Massi and coworkers demonstrated the potential for Re(I) tricarbonyl NHCcomplexes to facilitate photoredox-based reactions. [53] The authors demonstrated the viability of photoactive tricarbonyl Re(I) complexes bearing bidentate mixed pyridine-NHC ligands to promote fundamental classes of visible-light mediated photoredox-catalyzed reactions.…”

“…[53] In 2019, Bissember, Massi and coworkers demonstrated the potential for Re(I) tricarbonyl NHCcomplexes to facilitate photoredox-based reactions. [53] The authors demonstrated the viability of photoactive tricarbonyl Re(I) complexes bearing bidentate mixed pyridine-NHC ligands to promote fundamental classes of visible-light mediated photoredox-catalyzed reactions. In particular, atom-transfer radical addition (ATRA), hydrodehalogenation processes, and αamino CÀ H functionalization reactions were studied.…”

“…The halogen atom ligand also varies between Cl and Br (Scheme 19). [53] Complex 28 b exhibited the best catalytic performance in the photoredox-catalyzed radical addition of N-phenyl-1,2,3,4tetrahydroisoquinoline to methyl vinyl ketone under Brønsted acid, yielding 73 % of the final product in 24 h (Scheme 20a). The best performance catalysts for the Povarov-type reaction of N,N-dimethylaniline with N-phenylmaleimide, complexes 27-29, only afforded moderate yields (43-58 %) to the corresponding heterocyclic final product (Scheme 20b).…”

Rhenium-catalysed reactions in chemical synthesis: selected case studies

“…Of the C-C bond-forming reactions discussed above, the focus on directed C-H activation reactions has been a particularly noticeable over the last five years. Examples of photoactive rhenium complexes in photoredox catalysis 146,147 and photopolymerisation have emerged recently. 148 Beyond this, we suggest that more diverse applications of rhenium catalysis in chemical synthesis may be uncovered by moving past commercially available rhenium(I) and(VII) systems and exploring the opportunities provided by less established rhenium species.…”